3. What is a system?
Is an organized collection of interdependent
components that perform a function and which
are connected through the transfer of energy
and/or matter
All the parts are linked together and affect each
other.
Examples:
• Ecosystems in which various elements such as air, water, movement,
plants and animals work together to survive or perish.
• Organizations in which people, structures, and processes work
together to do business.
8. Large ecosystem -
biome
• A biome (or ecosystem) is a
climatically and geographically
defined area often with similar
communities of plants and animals.
• Biome movie
21. Global ecosystem - Gaia
The Gaia hypothesis is an ecological
hypothesis proposing that the biosphere and
the physical components of the Earth
(atmosphere, hydrosphere and lithosphere)
are closely integrated to form a complex
interacting system that maintains the
climatic and biogeochemical conditions on
Earth in a preferred homeostasis.
22.
23. Terminology
• Open system - where matter and energy is
exchange outside the system.
eg. Local ecosystems (biomes)
• Closed system – where only energy is
exchanged outside the system.
eg. Carbon, nitrogen, water, phosphate cycles
• Isolated system – neither heat nor energy is
exchanged.
eg. The cosmos?
30. Terminology
First law of thermodynamics – energy is
neither created nor destroyed
Second law of thermodynamics – in any
isolated system entropy tends to increase
spontaneously
Equilibrium – forward and reverse
reactions are equal - balance
34. Flows and storages
Two basic processes must occur in an ecosystem:
1. A cycling of chemical elements.
2. Flow of energy.
TRANSFERS: normally flow through a system
and involve a change in location.
TRANSFORMATIONS: lead to an interaction
within a system in the formation of a new
end product, or involve a change of state.
35.
36.
37. Components of a system:
1. Inputs such as
energy or matter.
Calories
Protein
38. 2. Flows of
matter or
energy within
the systems at Calori
es
certain rates.
Protei
n
39. 3.Outputs of
certain forms of
matter or energy
that flow out of
Waste
the system into Calorie
s Heat
sinks in the
environment.
Waste
Protei
n Matte
r
40. 4. Storage areas in
which energy or
matter can
accumulate for Calorie
various s
lengths of time
before being Protei
released. n
42. Positive and Negative
Feedback
• Positive feedback includes a sequence of
events that will cause a change in the same
direction as the stimulus and thereby
augments the change, moving the state of
the system even further from the equilibrium
point.
• Negative feedback systems include a
sequence of events that will cause an effect
that is in the opposite direction to the original
stimulus and thereby brings the system back
to its equilibrium position.
47. • Predator/prey relationships are usually
controlled by negative feedback where:
• The increase in prey-increase in predator-
decrease in prey decrease in
predatorincrease in prey---and so on in a
cyclical manner. The classic study in Northern
Canada between the Lynx and the hare
populations is famous for its regular 11 year
cycle of rising and falling populations.
48.
49. Models
What is a model?
• A representation or a simulation, could be
conceptual, physical, mathematical
How to evaluate a model?
• Does it explain past observations
• Does it agree with other models
• Does it predict accurately
50. Models
• What are the strengths and weakness of these
models?
• Determining if asteroids affected earth’s past but
craters not formed due to ice - see impact crater
Permafrost connecting ice layer
Brittleness of crust vs sand
• What problems might the aquarium model have?
Biodiversity, storages…
51. SUSTAINABILITY is the extent to which a
given interaction with the environment
exploits and utilizes the natural income
without causing long-term deterioration to the
natural capital.
